Extraordinary Canadian dance company Cas Public, in collaboration with Belgian youth theatre Kopergietery, returns to the Royal Opera House with 9, which takes dancer Cai Glover’s hearing impairment as an inspiration point. Through Beethoven’s Ninth Symphony, choreographer H?l?ne Blackburn uses dance to question how we capture the monumental grandeur of this music if, like Beethoven, our hearing is impaired. 9 plays with music and silence and celebrates difference in a work for children and adults.